Locking system for a blowout preventer

ABSTRACT

A locking system for a blowout preventer having a plurality of individually actuated hydraulic rams. A pilot operated locking valve for each ram for locking the ram in the closed position in which all of the locking valves are pilot operated to open and close simultaneously by two common pilot lines. The locking valves are of the positive shut-off shear-seal type. They include a hydraulic override so that if one ram is closed and locked, which puts all of the locking valves in the closed position, a second ram can still be closed by applying more pressure in the closing line of that ram than applied in the pilot closing line, all without interrupting the other locking valves.

[111 3,827,668 Aug. 6, 1974 LOCKING SYSTEM FOR A BLOWOUT PREVENTERInventors: Douwe De Vries; Samuel E.

Gilmore, both of Houston, Tex.

Assignee: C. Jim Stewart & Stevenson, Inc.,

Houston, Tex.

Filed: Oct. 5, 1972 Appl. No.: 295,344

US. Cl 251/1, 91/414, 137/495, 251/26, 251/31, 251/63.4

Int. Cl... E2lb 33/06, Fl5b 11/16, F15b 13/01 Field of Search 251/1;166/.6; 91/411, 91/414 References Cited UNITED STATES PATENTS 12/1924Hansen 251/1 X 6/1965 Rhodes et al. 166/.6

Primary Examiner-William R. Cline Assistant Examiner-Richard GerardAttorney, Agent, or FirmFulbright & Cooker [57] ABSTRACT A lockingsystem for a blowout preventer having a plurality of individuallyactuated hydraulic rams. A pilot operated locking valve for each ram forlocking the ram in the closed position in which all of the lockingvalves are pilot operated to open and close simultaneously by two commonpilot lines. The locking valves are of the positive shut-off shear-sealtype. They include a hydraulic override so that if one ram is closed andlocked, which puts all of the locking valves in the closed position, asecond ram can still be closed by applying more pressure in the closingline of that ram than applied in the pilot closing line, all withoutinterrupting the other locking valves.

3 Claims, 2 Drawing Figures Pmmtmim awn 3 ow em ,3 mm 9 ON l mm 1. ON m7 II n. 1 .ll- I w H. mm ov r mm BACKGROUND OF THE INVENTION It iscommon to use blowout preventers having a plurality of rams which openand close for closing off the bore of an oil and/or gas well. The ramsof the blowout preventers are generally hydraulically actuated by apiston and cylinder arrangement. In order to hold the rams in the closedposition, hydraulically operated mechanical locking devices aregenerally employed.

Of course, suitable hydraulic lines must be led between the blowoutpreventer and a source of fluid power to supply the hydraulic fluid forthe rams and the locking devices. If the blowout preventer is positionedunderwater, it is highly desirable to have a locking device of minimumsize and a minimum number of lines leading from the surface to theunderwater blowout preventer. The present invention is directed to animproved locking system for a blowout preventer which utilizes ahydraulic valve far smaller than the usual mechanical device and aminimum of control lines. The versatile positive shut-off locking valvescan be locked, opened, and overridden to perform the locking functionfor a plurality of rams.

SUMMARY The present invention is directed to providing a positivelocking system for a blowout preventer having a plurality ofindividually actuated hydraulic rams each of which includes a speciallocking valve in the closing line of the ram. In order to reduce theamount of control lines, all of the pilot operated locking valves areopened and closed simultaneously with only two common pilot lines.

If one ram is closed and locked, all of the locking valves are placed inthe closed position since they are all operated by common pilot lines.Another feature of the present invention is the ability of the lockingsystem to close a second ram without opening the locking valves byproviding the locking valves with a hydraulic override which is actuatedby applying more pressure in the closing line of the ram desired to beclosed then applied on the locking valve through the pilot line. Theoverride feature allows a locked valve to be opened, in order to closeits connected ram, without affecting the other locking valves on theother rams in the blowout preventer.

The present invention is further directed to a pilot operated lockingvalve having an override in which a valve element moves between an openand close position and is controlled by pilot actuated pistons. Thepiston opening the valve has an area exposed to the valve inlet in adirection to open the valve. When a greater force is applied from thevalve inlet against the opening piston than the closing force acting onthe closing piston, the valve will be overridden and opened to allowpassage of fluid therethrough, but will close when the inlet pressure isreduced.

Yet a further object is the provision of an override locking valvewherein the opening piston includes first and second separate butadjacent portions in which the second portion includes a piston ring andis exposed to the pilot opening line and the first portion includes apassageway in communication between the valve inlet and one end of thefirst portion for providing an override force from the valve inletagainst the valve element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, incross section, of the pilot operated locking valve of the presentinvention, and

FIG. 2 is a schematic view, partly in cross section, of a locking systemfor a blowout preventer.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to thedrawings, and particularly FIG. 2, the reference numeral 10 generallyrefers to a conventional blowout preventer having a plurality of rams12, 14, 16 and 18. Each of the rams conventionally has a hydraulicclosing line and a hydraulic opening line. Thus, the rams 12, 14, 16 and18 each includes a closing line 20, 22, 24 and 26, respectively. Inaddition, each of the rams 12, 14, 16 and 18 includes a hydraulicopening line 28, 30, 32 and 34, respectively. The rams may beconventional double acting piston and cylinder operated rams which closewhen hydraulic fluid is transmitted through their closing line whileexhausting fluid through the opening line, and open when hydraulic fluidis transmitted through their opening line while exhausting fluid throughtheir closing line. Of course, if the blowout preventer 10 is on theocean floor underwater, the closing lines 20, 22, 24 and 26 and theopening lines 28, 30, 32 and 34 must lead to the water surface to ahydraulic fluid power source for actuating the rams to the closed oropened position such as to shuttle valves 21, 23, 25 and 27,respectively, which preferably lead to two power sources.

The locking system of the present invention includes identical lockingvalves 40a, 40b, 40c and 40d in each of the closing lines 20, 22, 24 and26, respectively, which open to allow closing hydraulic fluid to pass toone or more of the rams 12, 14, 16 and 18 for closing the rams. After aram is closed, a locking valve must be closed to lock the ram closingpressure in to maintain the closed ram in a closed and locked position.When the rams are to be opened, the locking valve must open to allow theclosing fluid in the closing lines to exhaust through the lockingvalves. Each of the locking valves 40a, 40b, 40c and 40d are pilotoperated to be opened or closed. In order to reduce the number of linesleading to the blowout preventer 10, particularly when the blowoutpreventer 10 is underwater, a single pilot closing control line 42 and asingle pilot opening control line 44 are provided connected to each ofthe locking valves 40a, 40b, 40c and 40d for simultaneously applying ahydraulic closing or opening force to all of the locking valves.

Referring now to FIG. 1, a single locking valve 40ais shown and theremainder of the locking valves 40b, 40c and 40d are identical instructure and function. The valve 40a includes an inlet 46 and an outlet48 both of which are connected in the closing line 20 for passage andexhaust of hydraulic fluid therethrough to and from the ram 12. Valve40a includes a valve element I 50 such as a shear-seal type elementadapted to be tion to the pilot opening control line 44. A pilot closingpiston 56 is provided in communication with the closing port 52 and theclosing control line 42 which moves the valve element 50 to the closedposition when pressure is applied to the closing control line 42. Apilot opening piston generally indicated by the reference numeral 60 isprovided in communication with the opening port 54 and opening controlline 44 and is responsive to fluid pressure therein for indirectlymoving the valve element 50 upwardly by pushing a valve element carrier62. Valve element carrier 62 serves also as the primary opening pistonsubject to pressure applied between secondary opening piston 60 anditself. The secondary opening piston 60 includes a piston ring or seal66 whereby the first portion 60 will be movable in response to fluidpressure in the opening controlline 44. The primary piston and carrier62 includes a piston ring or seal 64, a port 68 and a passageway 70leading to the cavity between items 60 and 62. It is to be noted thatthe port 68 and passageway 70 are in fluid communication with the valveinlet 46 for allowing fluid from the inlet 46 to pass to the undersideof the carrier piston 62 to create a hydraulic override to move seal 50to open the valve 40a even when the valve 400 has moved to the closedposition by the closing pilot piston 56.

Assume that all of the rams 12, 14, 16 and 18 of the blowout preventerare open and it is desired to close one of the rams, for example ram 12.In that event, control pressure is transmitted through pilot openingcontrol line 44 and is applied against the pilot opening piston 60 inthe locking valve 40a and against the pilot opening pistons in all ofthe other locking valves 40]), 40c and 40d since all of the lockingvalves operate simultaneously from the two common pilot lines 44 and 42.Fluid pressure against the back of the secondary piston 60 moves thecarrier 62 and thereby the valve element 50 away from outlet port 48allowing communication between the inlet 46 and outlet 48 of the lockingvalve 40a, thereby opening valve 40a. Hydraulic fluid is thentransmitted through closing line and locking valve 40a to the ram 12 forclosing the ram 12. Fluid pressure in the pilot opening control line 44is bled off and fluid pressure is exerted through the pilot closingcontrol line 42 which is applied to the closing port 52 behind theclosing pilot piston 56 which now moves the valve element 50 intoposition over outlet port 48, as best seen in FIG. 1, blockingcommunication between the valve inlet 46 and the valve outlet 48 therebylocking the ram 12 in the closed position as soon as the fluid pressurein the closing line 20 is bled off. Since only the single control lines42 and 44 are used, the closing of locking valve 40a closes all of theother locking valves 40b, 40c and 40d even though the rams 14, 16 and 18remain in the open position.

In the event that it is then desired to close a second ram, such as ram14, the closed locking valve 401) would then be overridden by applying agreater pressure through the closing line 22 of ram 14 than is appliedto the locking valve 40b through the pilot closing control line 42. Forexample only, the pilot pressure in the control lines 42 and 44 may be1,500 psi and if 2,000 psi hydraulic pressure is applied through theclosing line 22, the locked locking valve 40b will be temporarily openedby the pressure in the closing line 22, without affecting the otherlocking valves 40a, 40c and 40d until the ram 14 is closed, and afterwhich, the locking valve 40b will thereafter close again to hold the ram14 in the closed position. That is, the higher pressure in the closingline 22 will pass through the inlet 46 of the valve 40b and through theport 68 and passageway to the underside of the primary opening pistonand carrier 62 and overcome the force of the lower pressure of the pilotclosing line 42 acting on the pilot closing piston 56. The higher forceacting on the piston portion 62 will move primary piston 62 upwardlymoving the valve element 50 away from the outlet 48 allowing fluidcommunication of the higher pressure from the inlet 46 through theoutlet 48 and the closing line 22 to close the ram 14. As soon as ram 14has been closed, the higher closing pressure in the closing line 22 isbled off and when the pressure in the closing line 22 is decreased belowthe pressure in the pilot closing line 42 the pilot closing pressure inline 42 will again force the pilot closing piston 56 downwardly movingthe valve element 50 into a closed position and locking the ram in theclosed position by holding the fluid behind the double acting ram 14.During this operation of closing the ram 14 the other locking valves40a, 40c and 40d will remain locked.

The present invention, therefore, is well adapted to carry out theobjects and attain the ends and advantages mentioned as well as othersinherent therein. While a presently preferred embodiment of theinvention has been given for the purpose of disclosure, numerous changesin the details of construction and arrangement of parts may be madewhich will readily suggest themselves to those skilled in the art andwhich are encompassed within the spirit of the invention and the scopeof the appended claims.

What is claimed is:

l. A locking system for a blowout preventer having a plurality ofhydraulically operated rams comprising,

a pilot operated locking valve for each ram, each said valve having aninlet and an outlet, the outlet of each valve connected to one of therams and the inlet of each valve connected to a separate source ofhydraulic fluid for closing the connected ram,

each valve having a pressure operated valve element for opening andclosing communication between the valve inlet and the outlet,

at single pilot control line connected to all of the valves on one sideof the valve elements for closing all of the valves thereby locking anyof the rams that have been closed in the closed position,

a single pilot control line connected to all of the valves on a secondside of the valve elements for opening all of the valves, and

an area on each valve element on said second side exposed to the inlet,said area being sufficiently large to open the associated valve when anoverriding pressure is provided at the inlet of any one valve greaterthan the pressure in the pilot control line closing said one valvethereby opening said one valve and closing the ram connected to said onevalve.

2. A locking system for an underwater blowout preventer having aplurality of hydraulically operated rams comprising,

a pilot operated locking valve for each ram, each said valve having aninlet and an outlet, the outlet of each valve connected to one of therams and the inlet of each valve connected to a separate source ofhydraulic fluid for closing the connected ram,

a valve element in each said valve for opening and closing communicationbetween the valve inlet and the outlet,

a first piston on one side of each valve element,

a pilot closing port in each valve communicating with the first pistonfor supplying fluid against the first piston for moving the element tothe closed position,

a single pilot closing control line connected to all of the pilotclosing ports for closing all of the valves thereby locking any of therams that have been closed in the closed position,

a second piston on a second side of each of the valve elements,

a pilot opening port in each valve communicating with the second pistonfor supplying fluid against the second piston for moving the element tothe open position,

the pilot opening ports for opening all of the valves,

each said second piston having an area exposed to the valve inlet in adirection to open said valve when a greater force is applied from thevalve inlet against the second piston area than the closing force on thefirst piston.

3. The aparatus of claim 2 wherein the second piston includes first andsecond separate adjacent portions, the second portion including a pistonring, and the first portion including a passageway in communicationbetween the valve inlet and the end of the first portion remote from thevalve element, said second portion being positioned between the firstportion and the pilot opening port.

1. A locking system for a blowout preventer having a plurality ofhydraulically operated rams comprising, a pilot operated locking valvefor each ram, each said valve having an inlet and an outlet, the outletof each valve connected to one of the rams and the inlet of each valveconnected to a separate source of hydraulic fluid for closing theconnected ram, each valve having a pressure operated valve element foropening and closing communication between the valve inlet and theoutlet, a single pilot control line connected to all of the valves onone side of the valve elements for closing all of the valves therebylocking any of the rams that have been closed in the closed position, asingle pilot control line connected to all of the valves on a secondside of the valve elements for opening all of the valves, and an area oneach valve element on said second side exposed to the inlet, said areabeing sufficiently large to open the associated valve when an overridingpressure is provided at the inlet of any one valve greater than thepressure in the pilot control line closing said one valve therebyopening said one valve and closing the ram connected to said one valve.2. A locking system for an underwater blowout preventer having aplurality of hydraulically operated rams comprising, a pilot operatedlocking valve for each ram, each said valve having an inlet and anoutlet, the outlet of each valve connected to one of the rams and theinlet of each valve connected to a separate source of hydraulic fluidfor closing the connected ram, a valve element in each said valve foropening and closing communication between the valve inlet and theoutlet, a first piston on one side of each valve element, a pilotclosing port in each valve communicating with the first piston forsupplying fluid against the first piston for moving the element to theclosed position, a single pilot closing control line connected to all ofthe pilot closing ports for closing all of the valves thereby lockingany of the rams that have been closed in the closed position, a secondpiston on a second side of each of the valve elements, a pilot openingport in each valve communicating with the second piston for supplyingfluid against the second piston for moving the element to the openposition, a single pilot opening control line connected to all of thepilot opening ports for opening all of the valves, each said secondpiston having an area exposed to the valve inlet in a direction to opensaid valve when a greater force is applied from the valve inlet againstthe second piston area than the closing force on the first piston. 3.The aparatus of claim 2 wherein the second piston includes first andsecond separate adjacent portions, the second portion including a pistonring, and the first portion including a passageway in communicationbetween the valve inlet and the end of the first portion remote from thevalve element, said second portion being positioned between the firstportion and the pilot opening port.